Ukraine鈥檚 president planned to address the U.N.鈥檚 most powerful body on Tuesday after even more grisly evidence emerged of . Western nations expelled dozens more of Moscow鈥檚 diplomats and proposed further sanctions as part of efforts to punish Russia for what they say are war crimes.

President Volodymyr Zelenskyy鈥檚 speech to the Security Council will be rich with symbolism, but the invitation and other displays of Western support are unlikely to alter the situation on the ground. He says his forces desperately need more powerful weaponry, some of which the West has been reluctant to give. Russia鈥檚 veto guarantees the body will take no action, and it was unclear whether its representatives would even remain in the chamber for the video address.

The head of NATO, meanwhile, warned that Russia is regrouping its forces in order to deploy them to eastern and southern Ukraine for a 鈥渃rucial phase of the war,鈥� and said that more 鈥渁trocities鈥� may come to light as Russian troops continue to pull back in the north.

鈥淲hen and if they withdraw their troops and Ukrainian troops take over, I鈥檓 afraid they will see more mass graves, more atrocities and more examples of of war crimes,鈥� NATO Secretary-General Jens Stoltenberg said.

Ukrainian officials said the bodies of at least 410 civilians have been found in towns around Kyiv that were recaptured from Russian forces and that a 鈥渢orture chamber鈥� was discovered in the town called Bucha, from which some of the grimmest details have emerged.

Police and other investigators walked the silent streets of Bucha on Tuesday, taking notes on bodies that residents showed them. Survivors who hid in their homes during the monthlong Russian occupation of the town, many of them past middle age, wandered past charred tanks and jagged window panes with plastic bags of food and other humanitarian aid. Red Cross workers checked in on intact homes.

Associated Press journalists in the town . Many appeared to have been shot at close range, and some had their hands bound or their flesh burned. A mass grave in a churchyard held bodies wrapped in plastic.

High-resolution satellite imagery by commercial provider Maxar Technologies, meanwhile, showed that many of the bodies had been lying in the open for weeks, during the time that Russian forces were in the town. The New York Times first reported on the images showing the dead.

U.S. Secretary of State Antony Blinken said the images from Bucha revealed 鈥渁 deliberate campaign to kill, to torture, to rape, to commit atrocities.鈥� He told journalists the reports were 鈥渕ore than credible鈥� and reinforce the determination of countries around the world to hold those responsible to account and to support Ukraine.

鈥淥nly non-humans are capable of this,鈥� said Angelica Chernomor, a refugee from Kyiv who crossed into Poland with her two children, and who had seen the photos from Bucha. 鈥淓ven if people live under a totalitarian regime, they must retain feelings, dignity, but they do not.鈥�

Chernomor is among the more than 4 million Ukrainians who have fled the country in the wake of the Feb. 24 invasion. More than 7 million more people have been displaced inside Ukraine, the U.N. migration agency estimates.

Russia has rejected allegations of atrocities, with officials repeatedly saying without evidence that the scenes were faked. Moscow said it would speak about Bucha at the U.N. on Tuesday, indicating its representatives will attend at least part of the meeting.

Russia has against its forces in the past by accusing its enemies of forging photos and video, and of using so-called crisis actors. Western officials and independent reporters say Russia spreads disinformation to mask its actions.

As Western leaders condemned the killings in Bucha, Italy, Spain and Denmark on Tuesday, following moves by Germany and France. Hundreds of Russian diplomats have been sent home since the start of the invasion, many accused of being spies.

Kremlin spokesman Dmitry Peskov called the expulsions a 鈥渟hort-sighted鈥� measure that would complicate communication and warned they would be met with 鈥渞eciprocal steps.鈥�

In another show of support, the European Union鈥檚 executive branch from Russia, in what would be the first sanctions from the bloc targeting the country鈥檚 lucrative energy industry over the war. European Union Commission President Ursula von der Leyen, who plans to travel to Kyiv to meet with Zelenskyy this week, linked the ban on coal imports, worth 4 billion euros ($4.4 billion) per year, to the 鈥渉einous crimes鈥� around Kyiv.

The 27-nation EU has been a steadfast backer of Ukraine since the Russian invasion began on Feb. 24 and has already pushed through four rounds of sanctions 鈥� but Ukrainians officials have begged for more.

Just hours before the latest proposal was announced, Ukraine鈥檚 Foreign Minister Dmytro Kuleba said that to prevent 鈥渘ew Buchas鈥� the West must impose the 鈥渕other of all sanctions鈥� 鈥� on Russian oil and gas. 鈥淎 few months of tightening your belts are worth thousands of saved lives,鈥� he said.

But Western nations are divided over how far to go. Some are calling for a boycott of Russian oil and gas imports, while Germany and others fear that such a move could plunge the continent . And countries from the NATO alliance have refused to hand over some of the most powerful weaponry Zelenskyy has asked for, like fighter jets.

Their provision of other weapons and equipment has been credited with helping Ukraine mount a stiffer than expected resistance to Russia鈥檚 overwhelming firepower. That resistance stopped Russian forces from overrunning the capital and other cities, and many troops have now withdrawn from areas around Kyiv.

But Western and Ukrainian officials say Russia is merely regrouping for another offensive.

鈥淢oscow is not giving up its ambitions in Ukraine,鈥� said Stoltenberg, the head of NATO. 鈥淲e expect a further push in the eastern and southern Ukraine to try to take the entire Donbas and to create a land bridge鈥� to the Crimea Peninsula, which Russia annexed in 2014. Russia-backed separatists in the Donbas have been fighting Ukrainian troops for the last eight years.

Stoltenberg insisted the alliance will stand ready to help Ukraine with military equipment, a day after Zelenskyy appealed for more weaponry.

The Ukrainian military says that, in the Donbas, Russia is focused on seizing the cities of Popasna and Rubizhne in the Donetsk and Luhansk regions and the Azov Sea port of Mariupol, which has seen weeks of heavy fighting at a staggering cost to the city and its residents.

The Ukrainian governor of Luhansk on Tuesday urged residents to stay inside, shut windows and doors, and prepare wet face masks after a Russian strike hit a storage tank holding nitric acid near Rubizhne, which the Russians have been trying to seize. The Russian military has not commented on the alleged strike, and it could not be independently verified.

Ukrainian Deputy Prime Minister Iryna Vereshchuk, meanwhile, said seven humanitarian corridors will be open on Tuesday, including from besieged Mariupol, where 1,500 civilians were able to escape in private vehicles on Monday, as well as the Russian-controlled Berdyansk.

But it was not immediately clear whether Russia has agreed to halt the fighting along the corridors. Previous efforts to bring civilians to safety through humanitarian corridors have failed because of renewed fighting.

An international Red Cross team gave up on entering Mariupol at least for Tuesday, after several days of trying to deliver aid to the besieged city and help escort civilians out.

鈥擮leksandr Stashevskyi, The Associated Press